1. Field of the Invention
The present invention relates to a device packaging tape that comprises a paper-made carrier tape and a resin-made, heat-sealing top tape for covering device pockets formed in the carrier tape to accommodate electronic devices such as chip resistors.
2. Description of the Related Art
Conventional packaging tapes for transporting electronic devices are disclosed in Japanese Patent Laid-open No. 6(1994)-331533 and No. 11(1999)-165786, for example. These packaging tapes, as shown in FIGS. 1 and 2 of the present application, include a thick, paper-made carrier tape 1 provided with a number of device-accommodating pockets 2 arranged at prescribed intervals longitudinally of the tape. The packaging tape also includes a bottom tape 3 and a top tape 5. The bottom tape 3, made of synthetic resin such as polyethylene, is stuck to the reverse side of the carrier tape 1. In a device-loading process, the carrier tape 1, with the bottom tape 3 attached thereto, is forwarded longitudinally (see the arrow in FIG. 1). In this state, electronic devices 4 are put into the pockets 2 of the carrier tape 1. Thereafter, the top tape 5 is attached to the obverse side of the carrier tape 1 for sealing the device-loaded pockets 2.
In the conventional packaging tape, the top tape 5 may be made of a thermoplastic synthetic resin such as polyethylene for enabling thermal adhesion to the carrier tape 1. As another option, the top tape 5 can be made of a non-thermoplastic resin, but applied with hot-melt adhesive on one side thereof. In either way, when pressed against the carrier tape 1 by heated presser rollers 6, as shown in FIGS. 1 and 2, the compressed parts of the top tape 5 become sticky and will be firmly attached to the carrier tape 1 as they cool down.
The conventional method, however, has the following drawback.
As noted above, the top tape 5 is pressed against the carrier tape 1 by the heated presser rollers 6 for attachment. In this process, the thermally melted resin parts of the top tape 5 (or applied adhesive) inundate paper fibers on the surface of the carrier tape 1. Then, the melted parts of the top tape 5 will be hardened, thereby trapping the paper fibers of the carrier tape 1. In this condition, when the top tape 5 is peeled off to take out the inside devices, some of the trapped paper fibers may be nipped out from the carrier tape 1, while the other may remain on the carrier tape 1 by slipping away from the trap of the top tape 5. In this latter case, the slipping paper fibers are rubbed with the trapping portions of the resin-made top tape 5. Consequently, static electricity is generated on the top tape 5, whereby the electronic devices accommodated in the device pockets 2 tend to be attracted to the top tape 5 to be peeled. Unfavorably, this may result in the loss of the electronic devices.